1. Field of the Invention
The present invention is related to a pixel structure and a method for repairing the same, and particularly, to a pixel structure capable of repairing the drain thereof and a method of repairing the same.
2. Description of the Prior Art
With the development of fabricating technology, liquid crystal displays (LCDs) have been widely used as display devices. LCDs have the advantages of higher definition, smaller volume, lighter weight, lower driving voltage and power consumption over other conventional display devices. LCDs are used in electronic display devices and computer hardware, such as portable televisions (TVs), mobile phones, camcorders, laptop computers, desktop display devices, and projector TVs. The liquid crystal molecules of the LCDs are rearranged by means of applying an electric field to change the lights passing through the liquid crystal molecules which results in the variation in light and shade effects. Until now, the development of LCDs has been roughly separated into two types: active-matrix LCDs and passive-matrix LCDs, wherein the active-matrix LCDs are the main product at present. In the active-matrix LCD, the thin film transistors (TFTs) or other active elements formed in the pixel electrode control the input of data to the LCD. Therefore, TFTs or other active elements are the main research and development targets in LCD technology.
Please refer to FIG. 1 and FIG. 2. FIG. 1 and FIG. 2 are schematic diagrams of a pixel structure 10 of a conventional LCD. FIG. 1 is a plane view diagram of the pixel structure 10, while FIG. 2 is a schematic cross-sectional view taken along the line A-A′-A″ in FIG. 1. Please refer to both FIG. 1 and FIG. 2. A pixel structure 10 formed on the substrate 12 comprises a first metal layer having a gate 14 and a gate line 16, a gate isolation layer 20, a semiconductor layer 22, a second metal layer 30 having a data line 24, a source 26, and a drain 28, a passivation layer 32, and a pixel electrode 34. The first metal layer is disposed on the substrate 12, and the gate isolation layer 20 is formed on the substrate 12 and covers the first metal layer. The second metal layer 30 is disposed on the gate isolation layer 20, and the source 26 and the drain 28 are disposed on each side of the gate 14. The passivation layer 32 is disposed on the gate isolation layer 20 and covers the second metal layer 30. The passivation layer 32 is covered by the pixel electrode 34. The pixel electrode 34 is electrically connected to the drain 28 via a contact hole 36, and the source 26 is electrically connected to the data line 24.
During the process of fabricating the conventional LCD, inappropriate control of process parameters or other unpredictable reasons may lead to defects, such as short circuits and broken circuits in the pixel structure 10. For example, the drain 28 in FIG. 2 is electrically connected to the pixel electrode 34 via the contact hole 36, so as to input a voltage from the data line 24 to the pixel electrode 34. However, there is a height difference in the drain 28 of the pixel structure 10 of the conventional LCD. A turning portion 38 between the upper and lower surface (as shown in FIG. 2) tends to break, in which causes a broken circuit, and thus the pixel structure 10 cannot be driven and are scraped, leading to problems such as insufficient yield rate and increase in costs.